Apparatus for manufacturing metals



Dc. 19, 1944. o. KRUH 2,365,346

APPARATUS FOR MANUFACTURING METALS Original Filed Oct. 6, 1939 06' VIC E4 POM/ l INVENTOR 0.5/45 KRl/H ATTORN EYS Patented Dec. 19, 1944 UNITEDSTATES PATENT OFFICE APPliRATIdS FOR METALS Original application October6, 1939, Serial No. 298,189, now Patent No. 2,255,549, dated September9, 1941. Divided and this application September 9, 1941, Serial No.410,203

3 Claims. (Cl. 266-15) This invention relates to apparatus for themetallurgy of metals suchas aluminum, beryllium, chromium, magnesium andthe like, as well as to their alloys, and has for its object certainimprovements in the apparatus. for recovering such metals and productionof their alloys,. as well as certain valuable by-products producedduring the practice of the invention.

In accordance with the invention the apparatus comprises a reductionchamber, a gas inlet for passing an inert gas into the reductionchamber, an upper outlet above the normal charge level of the reductionchamber for the escape of volatilized metal vapor and gaseous products,a lower outlet in the lower portion of the reduction chamber for theremoval of residues, a receptacle at the discharge end of the loweroutlet for rece'ivlng the residues from the reduction chamber, meansassociated with the lower outlet for opening and closing the same topermit intermittent discharge of the residues from the reduction chamberto the receptacle, high frequency induction means associated with thereduction chamber to heat the same to a highly elevated temperature, acondenser, a vapor conduit con" necting the upper part of the reductionchamber with the upper part of the condenser, high frequency inductionmeans associated with the condenser to heat the same, a valved gasconduit connecting the upper part of the condenser with the reductionchamber, said valved gas conduit being provided with a pump to circulategas from the condenser to the reduction chamber, and means for bleedingoff gaseous products of reduction from the system.

In the accompanying drawing, I have illustrated diagrammatically anapparatus illustrative of a practice of the invention. Briefly, theapparatus consists of an induction furnace l, a conduit 2, and acondenser 3 appropriately connecting one another. Each unit is coveredby a metal casing 4, and is also provided with a separate series ofcurrent and water-carrying copper tubes 5 embedded in an appropriatelayer of insulating material, 6, such as beryllium oxide adapted towithstand very'high temperatures. Each series of tubes 5 is connected toa transformer and a source of electrical current, so that each unit maybe heated by induction.

Referring to the specific construction of the repassageway of aconnecting member 10 secured to the furnace top nto which a fixed plugII is screwed. A conduit l2, with a valve 3|, of small diameter extendsthrough the plug for the introduction of a stream of inert gas adaptedto sweep the conduit 9 substantially clear of products of reductionwhich tend to accumulate therein.

A temperature indicating device i3 is associated with the top of thereduction chamber, and advantageously consists of a photo-electric bulbl4 and a pair of leads I5 connecting the bulb with the temperatureindicator; the bulb being located directly over a passagewaylliextending through the plug l I, in alignment with the passageway 9. Thepassageway I6 is provided with a suitable quartz window l1 adapted tolet light pass from the reduction furnace to the bulb IA. The top may beremoved from and non-leakably secured insulated passageway 24 leadinginto a heat in-' sulated receptacle 25 adapted to receive liquefiedproducts of reduction from the reaction chamber, such as ferro-siliconand the like. This receptacle is provided with a removable plugarrangement 26, similar to the one above described. Non-leakable jointsare provided so that pressures may be built up in the system.

The conduit 2 is also provided with a graphite lining and extends fromnear the top of the reduction chamber to the top of the condenser, asshown. An extension conduit 21 runs from the end of conduit 2 well intothe interior of the condenser 3.

The condenser is designed to contain a fused bath of salt or mixture ofsalts inert to the metals to be recovered, the bath to be maintained ata level that is just above the lower end of the extension conduit 21.The condenser is'provided with a removable plug 28 similar inconstruction to those described above.

As is shown by the drawing, the above-described apparatus is suitablyequipped with conduits and means for supplying a continuous stream ofinert gas, such as hydrogen or argon, successively through the reductionchamber, the conduit and the condenser. The drawing shows a conventionalmetal container or bottle 29 adapted to contain a supply of the inertgas. A conduit 3|! connects the outlet of the bottle with the lowerportion of the reduction chamber, and is also provided with an outletadapted to connect with the conduit l 2 provided in the plug 1 l of thereduction furnace.

A valved conduit 32 extends from the upper portion of the condenser, andconnects with a valved outlet 33 for the removal of undesirable carbonmonoxide and other gaseous reaction products from the system. Thisconduit advantageously connects with suitable receptacles for thecollection and treatment of the carbon monoxide.

Another conduit 34 connects with a purifying device 35, a conduit 36, apump 31, a valved conduit 38, which in turn connects with conduit 30leading through a preheater 39 into the reduction chamber. Saidpurifying device is adapted to remove such gases as nitrogen, oxygen andmoisture. Suitable chemicals for this purpose are molten aluminum,magnesium and other similarly reacting metals.

From what has been said above, the operation of the apparatus in thepractice of the process of the invention will be quite clear. A charge40 of the ore of the metal to be treated in oxide form, and anappropriate amount of carbonaceous reducing agent, such as coke, isintroduced in the reduction chamber 41. The top I may be removed for theintroduction of the charge, or the charge may be passed through thepassageway 9 on removing the connecting member III or the plug 1 I. Inorder to remove silica from the charge, an appropriate amount of ironfilings are admixed with the ore and carbon. The iron combines with thesilica to form a ferro-silicon alloy with the aid of the carbon. Theiron also acts as a conductor for induced electric current and thusfacilitates heating of the charge.

In order to condense the metal vapor to be produced, a suitable salt ormixture'of salts 42 is placed in condenser 3, in amount sufficient toprovide a fused bath of the salt at the level of or slightly above thelower end of extension conduit 21.

The entire system is heated by passing suitable electrical currentthrough copper tubes 5, and the tubes are cooled by passing watertherethrough, in a manner known to the art. As the charge reaches itsreduction temperature, carbon monoxide is formed, and perhaps some otherreaction gases. The charge is maintained under a predetermined andsufiiciently high pressure to retain the reduced metal within thereduction zone until the reaction has gone to substantial completion.

In a modification of the process, particularly for the production ofsuch metals as aluminum, beryllium, or their alloys, and chromium, theoxide of the metal to be treated is heated in the presence of asufiicientamount of the carbonaceous reducing agent to form a carbide ofthe metal, the charge being maintained at a predetermined pressure andtemperature to assure the formation of a carbide of the metal, and itsretention as such; so that the metal carbide is not decomposed orvaporized at that temperature and pres-' sure.

As the reaction continues in the reduction chamber, a by-product 43,such as ferro-silicon, is formed, which collects at the bottom of thechamber. This is tapped by means of the withdrawal oi plug 22, when theferro-silicon runs into and is deposited within receptacle 25. Duringthis operation, the system is maintained under appropriate pressure, aswill be shown by the pressure indicating device 44.

An inert gas, such as hydrogen or argon, contained in metal bottle 29 isthen fed through conduit 30 and the preheater 39 into the reductionchamber ll, at a temperature and pressure equal to that maintainedwithin the chamber. A sufflcient amount of the inert gas is thusintroduced to sweep out carbon monoxide still left in the system. Forthis purpose, the inert gas passes in, through, and over the charge intothe free space above the charge, thence through conduit 2 into thecondenser 3, from which it passes through conduits 32 and 33 to the openatmosphere or preferably to a holder or container 45 for subsequenttreatment to recover or utilize the valuable I carbon monoxide.

After the carbonmonoxide has thusbeen removed from the system, the valvein conduit 33 is closed, pump 31 is put in operation, and a continuousstream of inert gas from bottle 23 is passed successively throughreduction chamber 4|, conduit 2 and condenser 3. The inert gas leavingthe condenser is passed through the purifying device 35, in whichoxygen, nitrogen and moisture are removed. A certain amount of the gasis by-passed through conduit 3|, and passed into and downwardly throughthe passageway 3 in order to sweep the passageway clear of prodnets ofreduction that would otherwise tend to collect therein.

The temperature of the reduced metal in the reduction chamber is thenraised to its boiling point while still maintaining the system underpressure. In the case of the metal carbide, the temperature is raiseduntil the carbide is decomposed, and metal vapor is evolved. In eithercase, the resulting metal vapor is passed in the presence of the inertgas from the reduction chamber through the conduit to the condenser 3,in which the metal vapor is condensed. Due to th fact that the specificgravity of the fused molten salt in the condenser is lower than that ofthe metal to be recovered, the condensed metal particles coalesce andmerge into a liquid that settles out at the bottom in the form of alayer 45, which may be tapped as desired.

After the charge in the reduction chamber has been treated in the mannerindicated, a new charge is introduced. If, during the production ofmetal from the previous charge, the metal was converted to a carbide,the decomposition results in the release of carbon or graphite particlesthat are permitted to remain in the reduction chamber and to become apart of the carbonaceous reducing agent used to treat the newlyintroduced charge of ore.

It will be clear to those skilled in this art that a great saving ofheat can be eflected by circulating the inert gas from the condenser tothe reduction chamber. As the gas leaves the condenser it is highlyheated by the heat given up by the metal vapors as they condense. Toprevent substantial heat loss, the gas carrying coniiuit, and itsintermediate devices, are well insuated.

This application is a. division of my co-pending application Serial No.298,189, filed October 6.

1939, which issued September 9, 1941, as Patent 2,255,549, and whichclaims and describes in greater detail the operation of the apparatus inthe practice of the process of my invention.

I claim: 1. In apparatus for the recovery of metals, the

improvement comprising a reduction chamber, 'a

gas inlet for passing an inert gas into the reduction chamber, an upperoutlet above the normal charge level of the reduction chamber for theescape of volatilized metal vapor and gaseous products, a lower outletin the lower portion of the reduction chamber for the removal ofresidues, a receptacle at the discharg end of the ated with thecondenser to heat the same, a valved gas conduit connecting the upperpart of the condenser with the reduction chamber, said valved gasconduit being provided with a pump to circulate gas from the condenserto the reduction chamber, and means for bleeding off gaseous products ofreduction from the system.

lower outlet for receiving the residues from the reduction chamber,means associated with the lower outlet for opening and closing the sameto permit intermittent discharge of the residues from the reductionchamber to the receptacle, high frequency induction means associatedwith the reduction chamber to heat the same to a highly elevatedtemperature, a condenser, a vapor conduit connecting the upper partofthe reduction chamber with the upper part of the condenser, highfrequency induction means associsalts floating on the top of a bath ofcondensed molten metal collected in the condenser.

- OSIAS KRUH.

